Using separate read and write memory devices in a distributed storage network

ABSTRACT

A method begins by a processing module of a dispersed storage network (DSN) receiving a write request from a user to store encoded data slices and identifying a plurality of memory devices associated with the user. The method continues with the processing module selecting one or more memory devices based on whether the memory devices are read memory devices, write memory devices or read/write memory devices. The processing module then stores the encoded data slices in the selected memory devices and upon receiving a read request for the encoded data slices determines whether the encoded data slices have been consolidated in one or more read memories and when the encoded data slices have not been consolidated in one or more read memories, recovers the encoded data slices from one or more write memories of the plurality of memory devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility patent application claims priority pursuant to 35 U.S.C. §119(e) to U.S. Provisional Application No. 62/314,792, entitled “SELECTING A PROCESSING UNIT IN A DISPERSED STORAGE NETWORK”, filed Mar. 29, 2016, which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility patent application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to computer networks and more particularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/or store data. Such computing devices range from wireless smart phones, laptops, tablets, personal computers (PC), work stations, and video game devices, to data centers that support millions of web searches, stock trades, or on-line purchases every day. In general, a computing device includes a central processing unit (CPU), a memory system, user input/output interfaces, peripheral device interfaces, and an interconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using “cloud computing” to perform one or more computing functions (e.g., a service, an application, an algorithm, an arithmetic logic function, etc.) on behalf of the computer. Further, for large services, applications, and/or functions, cloud computing may be performed by multiple cloud computing resources in a distributed manner to improve the response time for completion of the service, application, and/or function. For example, Hadoop is an open source software framework that supports distributed applications enabling application execution by thousands of computers.

In addition to cloud computing, a computer may use “cloud storage” as part of its memory system. As is known, cloud storage enables a user, via its computer, to store files, applications, etc. on an Internet storage system. The Internet storage system may include a RAID (redundant array of independent disks) system and/or a dispersed storage system that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed or distributed storage network (DSN) in accordance with the present invention;

FIG. 2 is a schematic block diagram of an embodiment of a computing core in accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storage error encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an error encoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an error encoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of an encoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storage error decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an error decoding function in accordance with the present invention;

FIG. 9A is a schematic block diagram of another embodiment of a dispersed storage network in accordance with the present invention;

FIG. 9B is a flowchart illustrating an example of optimizing access to a memory system in accordance with the present invention;

FIG. 10 is a schematic block diagram of an embodiment of a dispersed or distributed storage network (DSN) in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, or distributed, storage network (DSN) 10 that includes a plurality of computing devices 12-16, a managing unit 18, an integrity processing unit 20, and a DSN memory 22. The components of the DSN 10 are coupled to a network 24, which may include one or more wireless and/or wire lined communication systems; one or more non-public intranet systems and/or public internet systems; and/or one or more local area networks (LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may be located at geographically different sites (e.g., one in Chicago, one in Milwaukee, etc.), at a common site, or a combination thereof. For example, if the DSN memory 22 includes eight storage units 36, each storage unit is located at a different site. As another example, if the DSN memory 22 includes eight storage units 36, all eight storage units are located at the same site. As yet another example, if the DSN memory 22 includes eight storage units 36, a first pair of storage units are at a first common site, a second pair of storage units are at a second common site, a third pair of storage units are at a third common site, and a fourth pair of storage units are at a fourth common site. Note that a DSN memory 22 may include more or less than eight storage units 36. Further note that each storage unit 36 includes a computing core (as shown in FIG. 2, or components thereof) and a plurality of memory devices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and the integrity processing unit 20 include a computing core 26, which includes network interfaces 30-33. Computing devices 12-16 may each be a portable computing device and/or a fixed computing device. A portable computing device may be a social networking device, a gaming device, a cell phone, a smart phone, a digital assistant, a digital music player, a digital video player, a laptop computer, a handheld computer, a tablet, a video game controller, and/or any other portable device that includes a computing core. A fixed computing device may be a computer (PC), a computer server, a cable set-top box, a satellite receiver, a television set, a printer, a fax machine, home entertainment equipment, a video game console, and/or any type of home or office computing equipment. Note that each of the managing unit 18 and the integrity processing unit 20 may be separate computing devices, may be a common computing device, and/or may be integrated into one or more of the computing devices 12-16 and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to support one or more communication links via the network 24 indirectly and/or directly. For example, interface 30 supports a communication link (e.g., wired, wireless, direct, via a LAN, via the network 24, etc.) between computing devices 14 and 16. As another example, interface 32 supports communication links (e.g., a wired connection, a wireless connection, a LAN connection, and/or any other type of connection to/from the network 24) between computing devices 12 and 16 and the DSN memory 22. As yet another example, interface 33 supports a communication link for each of the managing unit 18 and the integrity processing unit 20 to the network 24.

Computing devices 12 and 16 include a dispersed storage (DS) client module 34, which enables the computing device to dispersed storage error encode and decode data (e.g., data 40) as subsequently described with reference to one or more of FIGS. 3-8. In this example embodiment, computing device 16 functions as a dispersed storage processing agent for computing device 14. In this role, computing device 16 dispersed storage error encodes and decodes data on behalf of computing device 14. With the use of dispersed storage error encoding and decoding, the DSN 10 is tolerant of a significant number of storage unit failures (the number of failures is based on parameters of the dispersed storage error encoding function) without loss of data and without the need for a redundant or backup copies of the data. Further, the DSN 10 stores data for an indefinite period of time without data loss and in a secure manner (e.g., the system is very resistant to unauthorized attempts at accessing the data).

In operation, the managing unit 18 performs DS management services. For example, the managing unit 18 establishes distributed data storage parameters (e.g., vault creation, distributed storage parameters, security parameters, billing information, user profile information, etc.) for computing devices 12-14 individually or as part of a group of user devices. As a specific example, the managing unit 18 coordinates creation of a vault (e.g., a virtual memory block associated with a portion of an overall namespace of the DSN) within the DSN memory 22 for a user device, a group of devices, or for public access and establishes per vault dispersed storage (DS) error encoding parameters for a vault. The managing unit 18 facilitates storage of DS error encoding parameters for each vault by updating registry information of the DSN 10, where the registry information may be stored in the DSN memory 22, a computing device 12-16, the managing unit 18, and/or the integrity processing unit 20.

The managing unit 18 creates and stores user profile information (e.g., an access control list (ACL)) in local memory and/or within memory of the DSN memory 22. The user profile information includes authentication information, permissions, and/or the security parameters. The security parameters may include encryption/decryption scheme, one or more encryption keys, key generation scheme, and/or data encoding/decoding scheme.

The managing unit 18 creates billing information for a particular user, a user group, a vault access, public vault access, etc. For instance, the managing unit 18 tracks the number of times a user accesses a non-public vault and/or public vaults, which can be used to generate a per-access billing information. In another instance, the managing unit 18 tracks the amount of data stored and/or retrieved by a user device and/or a user group, which can be used to generate a per-data-amount billing information.

As another example, the managing unit 18 performs network operations, network administration, and/or network maintenance. Network operations includes authenticating user data allocation requests (e.g., read and/or write requests), managing creation of vaults, establishing authentication credentials for user devices, adding/deleting components (e.g., user devices, storage units, and/or computing devices with a DS client module 34) to/from the DSN 10, and/or establishing authentication credentials for the storage units 36. Network administration includes monitoring devices and/or units for failures, maintaining vault information, determining device and/or unit activation status, determining device and/or unit loading, and/or determining any other system level operation that affects the performance level of the DSN 10. Network maintenance includes facilitating replacing, upgrading, repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missing encoded data slices. At a high level, the integrity processing unit 20 performs rebuilding by periodically attempting to retrieve/list encoded data slices, and/or slice names of the encoded data slices, from the DSN memory 22. For retrieved encoded slices, they are checked for errors due to data corruption, outdated version, etc. If a slice includes an error, it is flagged as a ‘bad’ slice. For encoded data slices that were not received and/or not listed, they are flagged as missing slices. Bad and/or missing slices are subsequently rebuilt using other retrieved encoded data slices that are deemed to be good slices to produce rebuilt slices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core 26 that includes a processing module 50, a memory controller 52, main memory 54, a video graphics processing unit 55, an input/output (IO) controller 56, a peripheral component interconnect (PCI) interface 58, an IO interface module 60, at least one IO device interface module 62, a read only memory (ROM) basic input output system (BIOS) 64, and one or more memory interface modules. The one or more memory interface module(s) includes one or more of a universal serial bus (USB) interface module 66, a host bus adapter (HBA) interface module 68, a network interface module 70, a flash interface module 72, a hard drive interface module 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operating system (OS) file system interface (e.g., network file system (NFS), flash file system (FFS), disk file system (DFS), file transfer protocol (FTP), web-based distributed authoring and versioning (WebDAV), etc.) and/or a block memory interface (e.g., small computer system interface (SCSI), internet small computer system interface (iSCSI), etc.). The DSN interface module 76 and/or the network interface module 70 may function as one or more of the interface 30-33 of FIG. 1. Note that the IO device interface module 62 and/or the memory interface modules 66-76 may be collectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storage error encoding of data. When a computing device 12 or 16 has data to store it disperse storage error encodes the data in accordance with a dispersed storage error encoding process based on dispersed storage error encoding parameters. The dispersed storage error encoding parameters include an encoding function (e.g., information dispersal algorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding, non-systematic encoding, on-line codes, etc.), a data segmenting protocol (e.g., data segment size, fixed, variable, etc.), and per data segment encoding values. The per data segment encoding values include a total, or pillar width, number (T) of encoded data slices per encoding of a data segment (i.e., in a set of encoded data slices); a decode threshold number (D) of encoded data slices of a set of encoded data slices that are needed to recover the data segment; a read threshold number (R) of encoded data slices to indicate a number of encoded data slices per set to be read from storage for decoding of the data segment; and/or a write threshold number (W) to indicate a number of encoded data slices per set that must be accurately stored before the encoded data segment is deemed to have been properly stored. The dispersed storage error encoding parameters may further include slicing information (e.g., the number of encoded data slices that will be created for each data segment) and/or slice security information (e.g., per encoded data slice encryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as the encoding function (a generic example is shown in FIG. 4 and a specific example is shown in FIG. 5); the data segmenting protocol is to divide the data object into fixed sized data segments; and the per data segment encoding values include: a pillar width of 5, a decode threshold of 3, a read threshold of 4, and a write threshold of 4. In accordance with the data segmenting protocol, the computing device 12 or 16 divides the data (e.g., a file (e.g., text, video, audio, etc.), a data object, or other data arrangement) into a plurality of fixed sized data segments (e.g., 1 through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more). The number of data segments created is dependent of the size of the data and the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a data segment using the selected encoding function (e.g., Cauchy Reed-Solomon) to produce a set of encoded data slices. FIG. 4 illustrates a generic Cauchy Reed-Solomon encoding function, which includes an encoding matrix (EM), a data matrix (DM), and a coded matrix (CM). The size of the encoding matrix (EM) is dependent on the pillar width number (T) and the decode threshold number (D) of selected per data segment encoding values. To produce the data matrix (DM), the data segment is divided into a plurality of data blocks and the data blocks are arranged into D number of rows with Z data blocks per row. Note that Z is a function of the number of data blocks created from the data segment and the decode threshold number (D). The coded matrix is produced by matrix multiplying the data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encoding with a pillar number (T) of five and decode threshold number of three. In this example, a first data segment is divided into twelve data blocks (D1-D12). The coded matrix includes five rows of coded data blocks, where the first row of X11-X14 corresponds to a first encoded data slice (EDS 1_1), the second row of X21-X24 corresponds to a second encoded data slice (EDS 2_1), the third row of X31-X34 corresponds to a third encoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to a fourth encoded data slice (EDS 4_1), and the fifth row of X51-X54 corresponds to a fifth encoded data slice (EDS 5_1). Note that the second number of the EDS designation corresponds to the data segment number.

Returning to the discussion of FIG. 3, the computing device also creates a slice name (SN) for each encoded data slice (EDS) in the set of encoded data slices. A typical format for a slice name 80 is shown in FIG. 6. As shown, the slice name (SN) 80 includes a pillar number of the encoded data slice (e.g., one of 1-T), a data segment number (e.g., one of 1-Y), a vault identifier (ID), a data object identifier (ID), and may further include revision level information of the encoded data slices. The slice name functions as, at least part of, a DSN address for the encoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces a plurality of sets of encoded data slices, which are provided with their respective slice names to the storage units for storage. As shown, the first set of encoded data slices includes EDS 1_1 through EDS 5_1 and the first set of slice names includes SN 1_1 through SN 5_1 and the last set of encoded data slices includes EDS 1_Y through EDS 5_Y and the last set of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storage error decoding of a data object that was dispersed storage error encoded and stored in the example of FIG. 4. In this example, the computing device 12 or 16 retrieves from the storage units at least the decode threshold number of encoded data slices per data segment. As a specific example, the computing device retrieves a read threshold number of encoded data slices.

To recover a data segment from a decode threshold number of encoded data slices, the computing device uses a decoding function as shown in FIG. 8. As shown, the decoding function is essentially an inverse of the encoding function of FIG. 4. The coded matrix includes a decode threshold number of rows (e.g., three in this example) and the decoding matrix in an inversion of the encoding matrix that includes the corresponding rows of the coded matrix. For example, if the coded matrix includes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2, and 4, and then inverted to produce the decoding matrix.

FIG. 9A is a schematic block diagram of another embodiment of a dispersed storage network (DSN) that includes the computing device 16 of FIG. 1, the network 24 of FIG. 1, and a set of storage units 1-n. Each storage unit includes the processing module 84 of FIG. 10, a read memory, and a write memory. Each memory may be implemented utilizing the memory 88 of FIG. 10. Each storage unit may be implemented utilizing the computing device 36 of FIG. 1. The DSN functions to optimize access of a memory system, where the memory system includes read and write memories of the storage units.

In an example of operation of the optimizing of the access, when receiving an access request that includes a write slice request, the processing module 84 identifies a plurality of memories associated with an identifier of the access request. The identifier includes a slice name within a slice name range associated with the plurality of memories. The plurality of memories includes at least one read memory and at least one write memory. The identifying includes one or more of extracting a slice name from the write slice request, performing a deterministic function on the slice name to produce a list of memory identifiers, obtaining a status associated with a memory that is capable of reading and writing (e.g., identify a current status such as reading or writing), and performing a lookup based on the slice name to produce identifiers of the plurality of memories. For example, the processing module 84 of the storage unit 1 receives, via the network 24 from the computing device 16, an access request 1 and performs a lookup to identify the read memory 1 and the write memory 1 associated with the storage unit 1.

Having identified the plurality of memories, the processing module 84 selects a memory of the plurality of identify memories based on status (e.g., read-only, write, read/write) of each of the memories of the plurality of memories, where the processing unit 84 updates the status of each of the memories from time to time based on one or more of a quarantine request, a memory access error rate, a memory device performance level, etc. As an example of the selecting, the processing module 84 identifies a memory associated with a status of available for writing, i.e., a write only memory, a memory for temporary writing while a primary read/write memories unavailable during a maintenance operation. As a specific example, the processing module 84 identifies the write memory 1 when the status associated with the write memory 1 indicates for writing only.

Having selected the memory, the processing module 84 facilitates storing of one or more encoded data slices of the write slice request in the selected memory for writing. For example, the processing module 84 stores encoded data slices 1 to the write memory 1, where the access request 1 includes the encoded data slices 1.

When receiving another access request from the computing device 16 that includes a read slice request, the processing module 84 determines whether an encoded data slices associated with a slice name of the read slice request has been consolidated within a read memory. The determining includes identifying at least one encoded data slice stored in a write only memory that has not been transferred to the read memory. When the consolidation has not completed, the processing module 84 attempts to recover the encoded data slice from the write only memory and the read-only memory (e.g., when the exact location is unknown as during a transfer process), otherwise the processing module 84 times to recover the encoded data slice from the read-only memory. Having recovered the encoded data slice, the processing module 84 issues an access response to the computing device 16, where the access response includes the recovered encoded data slice.

When the consolidation has not completed, the processing module 84 further facilitates transfer of temporarily stored encoded data slices within the write only memory to the read only memory. For example, the processing module 84 facilitates moving transfer slices 1 from the write memory 1 to the read memory 1.

FIG. 9B is a flowchart illustrating an example of optimizing access to a memory system. The method includes a step 600 where a processing module (e.g., of a storage unit), when receiving a write request, identifies a plurality of memories associated with an identifier of the write request. The identifying includes one or more of extracting a slice name from the write request, performing a deterministic function on the slice name to produce a list of memory identifiers, and performing a lookup based on the slice name to produce identifiers of the plurality of memories.

The method continues at the step 602 where the processing module selects a memory of the plurality of memories based on a read/write status of each of the plurality of memories. The selecting includes determining a corresponding status of each memory and identifying a memory associated with a status favorably indicating available for writing (e.g., a write only memory that is available, a memory for temporarily writing while he primary read/write memory is unavailable during a maintenance operation).

The method continues at the step 604 where the processing module facilitates storing data of the write request in the selected memory. For example, the processing module stores one or more encoded data slices of the write request in the write only memory.

When receiving a read request, the method continues at the step 606 where the processing module determines whether data associated with the read request has been consolidated in a read memory. The determining may be based on identifying at least one encoded data slice stored in a write only memory that has not been transferred to the read memory. When the consolidation has not occurred, the method branches to the step where the processing module facilitates recovering the data from a write memory in the read memory. When the consolidation has occurred, the method continues to the next step.

When the consolidation has occurred, the method continues at step 608 where the processing module facilitates recovering the data from the read memory. For example, the processing module retrieves an encoded data slice associated with the read request from the read memory. As another example, the processing module retrieves the encoded data slice from a read/write memory when the read/write memory is available for reading. When the consolidation has not occurred, the method continues at the step 610 where the processing module facilitates recovering the data from the write memory and the read memory. For example, the processing module attempts to retrieve the encoded data slice from both the right memory in the read memory. The method continues at the step 612 where the processing module facilitates transfer of data from the write memory to the read memory. For example, the processing module transfers one or more encoded data slices as transfer slices from the write memory to the read memory and deletes the encoded data slices from the write memory subsequent to confirming that the transfer has successfully completed.

FIG. 10 is a diagram of an example of the distributed computing system performing a distributed storage and task processing operation. The distributed computing system includes a DS (distributed storage) client module 34 (which may be in computing device 14 and/or in computing device 16 of FIG. 1), a network 24, a plurality of storage units 1-n that includes two or more storage units 36 of FIG. 1 (which form at least a portion of DSN memory 22 of FIG. 1), a DS managing module (not shown), and a integrity verification module (not shown). The DS client module 34 includes an outbound DS processing section 80 and an inbound DS processing section 82. Each of the storage unit 1-n includes a controller 86, a processing module 84, memory 88, a DT (distributed task) execution module 90, and a DS client module 34.

In an example of operation, the DS client module 34 receives data 92 and one or more tasks 94 to be performed upon the data 92. The data 92 may be of any size and of any content, where, due to the size (e.g., greater than a few Terabytes), the content (e.g., secure data, etc.), and/or task(s) (e.g., MIPS intensive), distributed processing of the task(s) on the data is desired. For example, the data 92 may be one or more digital books, a copy of a company's emails, a large-scale Internet search, a video security file, one or more entertainment video files (e.g., television programs, movies, etc.), data files, and/or any other large amount of data (e.g., greater than a few Terabytes).

Within the DS client module 34, the outbound DS processing section 80 receives the data 92 and the task(s) 94. The outbound DS processing section 80 processes the data 92 to produce slice groupings 96. As an example of such processing, the outbound DS processing section 80 partitions the data 92 into a plurality of data partitions. For each data partition, the outbound DS processing section 80 dispersed storage (DS) error encodes the data partition to produce encoded data slices and groups the encoded data slices into a slice grouping 96. In addition, the outbound DS processing section 80 partitions the task 94 into partial tasks 98, where the number of partial tasks 98 may correspond to the number of slice groupings 96.

The outbound DS processing section 80 then sends, via the network 24, the slice groupings 96 and the partial tasks 98 to the storage unit 1-n of the DSN memory 22 of FIG. 1. For example, the outbound DS processing section 80 sends slice group 1 and partial task 1 to storage unit 1. As another example, the outbound DS processing section 80 sends slice group #n and partial task #n to storage unit #n.

Each storage unit performs its partial task 98 upon its slice group 96 to produce partial results 102. For example, storage unit #1 performs partial task #1 on slice group #1 to produce a partial result #1, for results. As a more specific example, slice group #1 corresponds to a data partition of a series of digital books and the partial task #1 corresponds to searching for specific phrases, recording where the phrase is found, and establishing a phrase count. In this more specific example, the partial result #1 includes information as to where the phrase was found and includes the phrase count.

Upon completion of generating their respective partial results 102, the storage units send, via the network 24, their partial results 102 to the inbound DS processing section 82 of the DS client module 34. The inbound DS processing section 82 processes the received partial results 102 to produce a result 104. Continuing with the specific example of the preceding paragraph, the inbound DS processing section 82 combines the phrase count from each of the storage unit 36 to produce a total phrase count. In addition, the inbound DS processing section 82 combines the ‘where the phrase was found’ information from each of the storage unit 36 within their respective data partitions to produce ‘where the phrase was found’ information for the series of digital books.

In another example of operation, the DS client module 34 requests retrieval of stored data within the memory of the storage unit 36 (e.g., memory of the DSN memory). In this example, the task 94 is retrieve data stored in the memory of the DSN memory. Accordingly, the outbound DS processing section 80 converts the task 94 into a plurality of partial tasks 98 and sends the partial tasks 98 to the respective storage unit 1-n.

In response to the partial task 98 of retrieving stored data, a storage unit 36 identifies the corresponding encoded data slices 100 and retrieves them. For example, storage unit #1 receives partial task #1 and retrieves, in response thereto, retrieved slices #1. The storage unit 36 send their respective retrieved slices 100 to the inbound DS processing section 82 via the network 24.

The inbound DS processing section 82 converts the retrieved slices 100 into data 92. For example, the inbound DS processing section 82 de-groups the retrieved slices 100 to produce encoded slices per data partition. The inbound DS processing section 82 then DS error decodes the encoded slices per data partition to produce data partitions. The inbound DS processing section 82 de-partitions the data partitions to recapture the data 92.

It is noted that terminologies as may be used herein such as bit stream, stream, signal sequence, etc. (or their equivalents) have been used interchangeably to describe digital information whose content corresponds to any of a number of desired types (e.g., data, video, speech, audio, etc. any of which may generally be referred to as ‘data’).

As may be used herein, the terms “substantially” and “approximately” provides an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to fifty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. Such relativity between items ranges from a difference of a few percent to magnitude differences. As may also be used herein, the term(s) “configured to”, “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for an example of indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. As may even further be used herein, the term “configured to”, “operable to”, “coupled to”, or “operably coupled to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform, when activated, one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater magnitude than signal 2, a favorable comparison may be achieved when the magnitude of signal 1 is greater than that of signal 2 or when the magnitude of signal 2 is less than that of signal 1. As may be used herein, the term “compares unfavorably”, indicates that a comparison between two or more items, signals, etc., fails to provide the desired relationship.

As may also be used herein, the terms “processing module”, “processing circuit”, “processor”, and/or “processing unit” may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module, module, processing circuit, and/or processing unit may be, or further include, memory and/or an integrated memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of another processing module, module, processing circuit, and/or processing unit. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, module, processing circuit, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that if the processing module, module, processing circuit, and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element may store, and the processing module, module, processing circuit, and/or processing unit executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the Figures. Such a memory device or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claims. Further, the boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claims. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof.

In addition, a flow diagram may include a “start” and/or “continue” indication. The “start” and “continue” indications reflect that the steps presented can optionally be incorporated in or otherwise used in conjunction with other routines. In this context, “start” indicates the beginning of the first step presented and may be preceded by other activities not specifically shown. Further, the “continue” indication reflects that the steps presented may be performed multiple times and/or may be succeeded by other activities not specifically shown. Further, while a flow diagram indicates a particular ordering of steps, other orderings are likewise possible provided that the principles of causality are maintained.

The one or more embodiments are used herein to illustrate one or more aspects, one or more features, one or more concepts, and/or one or more examples. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones.

Unless specifically stated to the contra, signals to, from, and/or between elements in a figure of any of the figures presented herein may be analog or digital, continuous time or discrete time, and single-ended or differential. For instance, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more particular architectures are described herein, other architectures can likewise be implemented that use one or more data buses not expressly shown, direct connectivity between elements, and/or indirect coupling between other elements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of the embodiments. A module implements one or more functions via a device such as a processor or other processing device or other hardware that may include or operate in association with a memory that stores operational instructions. A module may operate independently and/or in conjunction with software and/or firmware. As also used herein, a module may contain one or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes one or more memory elements. A memory element may be a separate memory device, multiple memory devices, or a set of memory locations within a memory device. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. The memory device may be in a form a solid state memory, a hard drive memory, cloud memory, thumb drive, server memory, computing device memory, and/or other physical medium for storing digital information.

While particular combinations of various functions and features of the one or more embodiments have been expressly described herein, other combinations of these features and functions are likewise possible. The present disclosure is not limited by the particular examples disclosed herein and expressly incorporates these other combinations. 

What is claimed is:
 1. A method for execution by one or more processing modules of one or more computing devices of a dispersed storage network (DSN), the method comprises: receiving a write request from a user to store encoded data slices; identifying a plurality of memory devices associated with the user; selecting one or more memory devices of the plurality of memory devices, based on a status of each of the memory devices of the plurality of memory devices, wherein the status of the one or more memory devices of the plurality of memory devices is based on the one or more memory devices of the plurality of memory devices being at least one of read memory devices, write memory devices or read/write memory devices; storing the encoded data slices in the one or more selected memory devices of the plurality of memory devices; receiving a read request for the encoded data slices; determining whether the encoded data slices have been consolidated in one or more read memories; and when the encoded data slices have not been consolidated in one or more read memories, recovering at least one of the encoded data slices from one or more write memories of the plurality of memory devices.
 2. The method of claim 1, wherein the identifying a plurality of memory devices associated with the user is based on at least one of extracting an encoded data slice name from the write request, performing a deterministic function on the encoded data slice name to produce a list of memory identifiers, or performing a lookup based on the encoded data slice name to produce identities for each of the plurality of memories.
 3. The method of claim 1, wherein the selecting further includes determining a corresponding status of each of the memory devices of the plurality of memory devices and identifying a memory associated with a status indicating availability for writing.
 4. The method of claim 1, wherein the determining whether the encoded data slices have been consolidated in one or more read memories is based on at least one encoded data slice stored in a write only memory that has not been transferred to the read memory.
 5. The method of claim 1, wherein the storing the encoded data slices in the one or more selected memory devices of the plurality of memory devices includes storing one or more encoded data slices in write only memory.
 6. The method of claim 1 further comprises: transferring, by the one or more processing modules, one or more encoded data slices from the write memory to the read memory and deleting the encoded data slices from the write memory subsequent to confirming that the transferring has successfully completed.
 7. The method of claim 1, wherein the memory devices of the plurality of memory devices include at least read memory devices and write memory devices, and all the memory devices are addressable by encoded data slice names within a same encoded data slice name range.
 8. The method of claim 7, wherein the same encoded data slice name range is used for at least two different storage units.
 9. The method of claim 7, wherein the same encoded data slice name range is used for at least two different memory devices statuses.
 10. The method of claim 7, wherein the read memory devices service all read requests for the encoded data slices and the write memory devices service all write requests for the encoded data slices.
 11. A computer readable memory comprises: a first memory element that stores operational instructions that, when executed by a computing device of a dispersed storage network (DSN), causes the computing device to: receive a write request from a user to store encoded data slices; identify a plurality of memory devices associated with the user; select one or more memory devices of the plurality of memory devices, based on a status of each of the memory devices of the plurality of memory devices, wherein the status of the one or more memory devices of the plurality of memory devices is based on the one or more memory devices of the plurality of memory devices being at least one of read memory devices, write memory devices or read/write memory devices; store the encoded data slices in the one or more selected memory devices of the plurality of memory devices; receive a read request for the encoded data slices; determine whether the encoded data slices have been consolidated in one or more read memories; and when the encoded data slices have not been consolidated in one or more read memories, recover at least one of the encoded data slices from one or more write memories of the plurality of memory devices.
 12. The computer readable memory of claim 11, further comprises: identify the plurality of memory devices associated with the user based on at least one of extracting an encoded data slice name from the write request, performing a deterministic function on the encoded data slice name to produce a list of memory identifiers, or performing a lookup based on the encoded data slice name to produce identities for each of the plurality of memories.
 13. The computer readable memory of claim 11, wherein the select one or more memory devices of the plurality of memory devices further comprises: determine a corresponding status of each of the memory devices of the plurality of memory devices and identify a memory associated with a status indicating availability for writing.
 14. The computer readable memory of claim 11, further comprises: determine whether the encoded data slices have been consolidated in one or more read memories based on at least one encoded data slice stored in a write only memory that has not been transferred to the read memory.
 15. The computer readable memory of claim 11, wherein the store the encoded data slices in the one or more selected memory devices of the plurality of memory devices further comprises: store one or more encoded data slices in write only memory.
 16. The computer readable memory of claim 11, further comprises: transfer one or more encoded data slices from the write memory to the read memory; and delete the encoded data slices from the write memory subsequent to confirming that the transferring has successfully completed.
 17. The computer readable memory of claim 11, wherein the memory devices of the plurality of memory devices include at least read memory devices and write memory devices, and all the memory devices are addressable by encoded data slice names within a same encoded data slice name range.
 18. The computer readable memory of claim 11, wherein the same encoded data slice name range is used for at least two different storage units.
 19. The computer readable memory of claim 11, wherein the same encoded data slice name range is used for at least two different memory devices statuses.
 20. The computer readable memory of claim 11, wherein the read memory devices service all read requests for the encoded data slices and the write memory devices service all write requests for the encoded data slices. 